Sunken 8th continent reveals its buried secrets

A proposed world map showing the eighth continent Zealandia. Though most of this continent is submerged beneath the ocean, scientists say it has all the geologic hallmarks of a separate continent.
(Nick Mortimer/GNS Science)

A journey to plumb the remote ocean depths has revealed that Earth does indeed have an eighth continent.

A nine-week voyage took scientists from around the world to drill and explore the seafloor off New Zealand and Australia. They found evidence of land-based fossils, revealing that the ancient landmass wasn't always buried beneath the waves.

"Zealandia, a sunken continent long lost beneath the oceans, is giving up its 60 million-year-old secrets through scientific ocean drilling," Jamie Allan, program director in the U.S. National Science Foundation's Division of Ocean Sciences, said in a statement. [Photos: The World's Weirdest Geological Formations]

Lost 8th continent

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Earlier this year, scientists argued that the known seven continents had a long-lost brother – Zealandia, a narrow strip of land that encompasses New Zealand and lies off the east coast of Australia, and whose landmass is mostly 3,280 feet (1,000 meters) below sea level beneath the ocean's surface. Among the evidence for Zealandia: The crust that makes up Zealandia is much shallower than the surrounding oceanic crust, and its geologic makeup looks more like continental versus oceanic crust. What's more, a narrow strip of oceanic crust separates Australia from Zealandia, which suggests the two landmasses were separate.

However, the area is so remote that few geologists had explored the region.

To answer questions about the mysterious continent, scientists aboard the JOIDES Resolution, a research drilling vessel, drilled sediment cores from six sites along the ocean seabed that makes up Zealandia. The cores plumbed 8,202 feet (2,500 m) below the surface, revealing 70 million years of the ancient continent's history.

The team found a treasure trove of fossils that reveal Zealandia wasn't always under the ocean.

"More than 8,000 specimens were studied, and several hundred fossil species were identified," expedition co-chief scientist Gerald Dickens of Rice University in Texas, said in statement. "The discovery of microscopic shells of organisms that lived in warm shallow seas, and of spores and pollen from land plants, reveal that the geography and climate of Zealandia were dramatically different in the past."

About 100 million years ago, Australia, Antarctica and Zealandia were all part of a mega-continent. The new drilling revealed that although Zealandia split off from these regions and sank below water about 80 million years ago, the chain of volcanism that makes up the Pacific's "Ring of Fire" may have caused Zealandia to buckle about 40 million to 50 million years ago, which also dramatically reshaped the landscape.

The findings could reveal how plants and animals dispersed across the South Pacific. In the past, this area provided some shallow seas and some strips of land to allow species to migrate and move between regions, the researchers said.